scholarly journals Reduction of exposure to simulated respiratory aerosols using ventilation, physical distancing, and universal masking

2021 ◽  
Author(s):  
Jayme P. Coyle ◽  
Raymond C Derk ◽  
William G Lindsley ◽  
Theresa Boots ◽  
Francoise M. Blachere ◽  
...  
Keyword(s):  
Indoor Environment ◽  
Respiratory Activity ◽  
Aerosol Particles ◽  
Inhalation Exposure ◽  
Mitigation Strategies ◽  
Engineering Controls ◽  
Particle Exposure ◽  
Adequate Ventilation ◽  
Respiratory Droplets ◽  
Indoor Spaces

To limit community spread of SARS-CoV-2, CDC recommends universal masking indoors, maintaining 1.8 m of physical distancing, adequate ventilation, and avoiding crowded indoor spaces. Several studies have examined the independent influence of each control strategy in mitigating transmission in isolation, yet controls are often implemented concomitantly within an indoor environment. To address the influence of physical distancing, universal masking, and ventilation on very fine respiratory droplets and aerosol particle exposure, a simulator that coughed and exhaled aerosols (the source) and a second breathing simulator (the recipient) were placed in an exposure chamber. When controlling for the other two mitigation strategies, universal masking with 3-ply cotton masks reduced exposure to 0.3-3 μm coughed and exhaled aerosol particles by > 77% compared to unmasked tests, whereas physical distancing (0.9 or 1.8 m) significantly changed exposure to cough but not exhaled aerosols. The effectiveness of ventilation depended upon the respiratory activity, i.e., coughing or breathing, as well as the duration of exposure time. Our results demonstrate that a combination of administrative and engineering controls can reduce personal inhalation exposure to potentially infectious very fine respiratory droplets and aerosol particles within an indoor environment.

scholarly journals Aerial Transmission of the SARS-CoV-2 Virus through Environmental E-Cigarette Aerosols: Implications for Public Policies

2021 ◽  
Vol 18 (4) ◽  
pp. 1437
Author(s):  
Roberto A. Sussman ◽  
Eliana Golberstein ◽  
Riccardo Polosa
Keyword(s):  
Emission Rate ◽  
Respiratory Activity ◽  
Separation Distance ◽  
Mitigation Strategies ◽  
Relative Risks ◽  
Respiratory Flow ◽  
Outdoor Spaces ◽  
Direct Exposure ◽  
Social Separation ◽  
Indoor Spaces

We discuss the implications of possible contagion of COVID-19 through e-cigarette aerosol (ECA) for prevention and mitigation strategies during the current pandemic. This is a relevant issue when millions of vapers (and smokers) must remain under indoor confinement and/or share public outdoor spaces with non-users. The fact that the respiratory flow associated with vaping is visible (as opposed to other respiratory activities) clearly delineates a safety distance of 1–2 m along the exhaled jet to prevent direct exposure. Vaping is a relatively infrequent and intermittent respiratory activity for which we infer a mean emission rate of 79.82 droplets per puff (6–200, standard deviation 74.66) comparable to mouth breathing, it adds into shared indoor spaces (home and restaurant scenarios) a 1% extra risk of indirect COVID-19 contagion with respect to a “control case” of existing unavoidable risk from continuous breathing. As a comparative reference, this added relative risk increases to 44–176% for speaking 6–24 min per hour and 260% for coughing every 2 min. Mechanical ventilation decreases absolute emission levels but keeps the same relative risks. As long as direct exposure to the visible exhaled jet is avoided, wearing of face masks effectively protects bystanders and keeps risk estimates very low. As a consequence, protection from possible COVID-19 contagion through vaping emissions does not require extra interventions besides the standard recommendations to the general population: keeping a social separation distance of 2 m and wearing of face masks.

scholarly journals Efficacy of Ventilation, HEPA Air Cleaners, Universal Masking, and Physical Distancing for Reducing Exposure to Simulated Exhaled Aerosols in a Meeting Room

Viruses ◽  
2021 ◽  
Vol 13 (12) ◽  
pp. 2536
Author(s):  
Jayme P. Coyle ◽  
Raymond C. Derk ◽  
William G. Lindsley ◽  
Francoise M. Blachere ◽  
Theresa Boots ◽  
...  
Keyword(s):  
Indoor Environment ◽  
Aerosol Particles ◽  
Personal Exposure ◽  
Mitigation Strategies ◽  
Face To Face ◽  
Meeting Room ◽  
Aerosol Exposure ◽  
Fine Aerosol ◽  
Unit Increase ◽  
Air Cleaners

There is strong evidence associating the indoor environment with transmission of SARS-CoV-2, the virus that causes COVID-19. SARS-CoV-2 can spread by exposure to droplets and very fine aerosol particles from respiratory fluids that are released by infected persons. Layered mitigation strategies, including but not limited to maintaining physical distancing, adequate ventilation, universal masking, avoiding overcrowding, and vaccination, have shown to be effective in reducing the spread of SARS-CoV-2 within the indoor environment. Here, we examine the effect of mitigation strategies on reducing the risk of exposure to simulated respiratory aerosol particles within a classroom-style meeting room. To quantify exposure of uninfected individuals (Recipients), surrogate respiratory aerosol particles were generated by a breathing simulator with a headform (Source) that mimicked breath exhalations. Recipients, represented by three breathing simulators with manikin headforms, were placed in a meeting room and affixed with optical particle counters to measure 0.3–3 µm aerosol particles. Universal masking of all breathing simulators with a 3-ply cotton mask reduced aerosol exposure by 50% or more compared to scenarios with simulators unmasked. While evaluating the effect of Source placement, Recipients had the highest exposure at 0.9 m in a face-to-face orientation. Ventilation reduced exposure by approximately 5% per unit increase in air change per hour (ACH), irrespective of whether increases in ACH were by the HVAC system or portable HEPA air cleaners. The results demonstrate that mitigation strategies, such as universal masking and increasing ventilation, reduce personal exposure to respiratory aerosols within a meeting room. While universal masking remains a key component of a layered mitigation strategy of exposure reduction, increasing ventilation via system HVAC or portable HEPA air cleaners further reduces exposure.

The Potential for Transmission of Coronaviruses via Sports Equipment; A Cricket Case Study

2021 ◽  
Author(s):  
Rory England ◽  
Nicholas Peirce ◽  
Joseph Torresi ◽  
Sean Mitchell ◽  
Andy Harland
Keyword(s):  
Viral Load ◽  
Mitigation Strategies ◽  
Infected Person ◽  
Review Of Literature ◽  
Airborne Transmission ◽  
Social Distancing ◽  
Transmission Pathways ◽  
Respiratory Droplets

AbstractA review of literature on the role of fomites in transmission of coronaviruses informed the development of a framework which was used to qualitatively analyse a cricket case study, where equipment is shared and passed around, and identify potential mitigation strategies. A range of pathways were identified that might in theory allow coronavirus transmission from an infected person to a non-infected person via communal or personal equipment fomites or both. Eighteen percent of potential fomite based interactions were found to be non-essential to play including all contact with another persons equipment. Six opportunities to interrupt the transmission pathway were identified, including the recommendation to screen participants for symptoms prior to play. Social distancing between participants and avoiding unnecessary surface contact provides two opportunities; firstly to avoid equipment exposure to infected respiratory droplets and secondly to avoid uninfected participants touching potential fomites. Hand sanitisation and equipment sanitisation provide two further opportunities by directly inactivating coronavirus. Preventing players from touching their mucosal membranes with their hands represents the sixth potential interruption. Whilst potential fomite transmission pathways were identified, evidence suggests that viral load will be substantially reduced during surface transfer. Mitigation strategies could further reduce potential fomites, suggesting that by comparison, direct airborne transmission presents the greater risk in cricket.

scholarly journals Generation and Characterization of Indoor Fungal Aerosols for Inhalation Studies

2016 ◽  
Vol 82 (8) ◽  
pp. 2479-2493 ◽  
Author(s):  
Anne Mette Madsen ◽  
Søren T. Larsen ◽  
Ismo K. Koponen ◽  
Kirsten I. Kling ◽  
Afnan Barooni ◽  
...  
Keyword(s):  
Species Composition ◽  
Indoor Environment ◽  
Building Materials ◽  
Inhalation Exposure ◽  
Single Species ◽  
Fungal Species ◽  
Exposure Level ◽  
Exposure System ◽  
Content Type ◽  
Water Damage

ABSTRACTIn the indoor environment, people are exposed to several fungal species. Evident dampness is associated with increased respiratory symptoms. To examine the immune responses associated with fungal exposure, mice are often exposed to a single species grown on an agar medium. The aim of this study was to develop an inhalation exposure system to be able to examine responses in mice exposed to mixed fungal species aerosolized from fungus-infested building materials. Indoor airborne fungi were sampled and cultivated on gypsum boards. Aerosols were characterized and compared with aerosols in homes. Aerosols containing 107CFU of fungi/m3air were generated repeatedly from fungus-infested gypsum boards in a mouse exposure chamber. Aerosols containedAspergillus nidulans,Aspergillus niger,Aspergillus ustus,Aspergillus versicolor,Chaetomium globosum,Cladosporiumherbarum,Penicillium brevicompactum,Penicillium camemberti,Penicillium chrysogenum,Penicillium commune,Penicillium glabrum,Penicillium olsonii,Penicillium rugulosum,Stachybotrys chartarum, andWallemia sebi. They were all among the most abundant airborne species identified in 28 homes. Nine species from gypsum boards and 11 species in the homes are associated with water damage. Most fungi were present as single spores, but chains and clusters of different species and fragments were also present. The variation in exposure level during the 60 min of aerosol generation was similar to the variation measured in homes. Through aerosolization of fungi from the indoor environment, cultured on gypsum boards, it was possible to generate realistic aerosols in terms of species composition, concentration, and particle sizes. The inhalation-exposure system can be used to study responses to indoor fungi associated with water damage and the importance of fungal species composition.

scholarly journals A risk control framework for safe manufacturing workstations in view of COVID-19

2020 ◽  
Vol 327 ◽  
pp. 03007
Author(s):  
Ebly Sanchez ◽  
Knut Åkesson
Keyword(s):  
Problem Solving ◽  
Manufacturing Industry ◽  
Close Contact ◽  
Mitigation Strategies ◽  
Assessment Model ◽  
Protection Measures ◽  
Industrial Plants ◽  
Engineering Controls ◽  
Risk Levels ◽  
Control Framework

The manufacturing industry resumes operations after the COVID-19 pandemic supported by return-to-work guidelines, which are mostly personal protection measures for the workers and employees. In this paper, we propose a framework for assessing risk at the workstation level by linking the risk levels to possible mitigation strategies that can be implemented using standard operating procedures (SOP), 5S and problem-solving. Within industrial plants, operators work in close contact with coworkers and supervisors, and they are also sharing tools and machines. It is therefore, essential to develop strategies that reduce the operator’s exposure to viruses in the workplace. The purpose of this work is that when implemented, the risk assessment model and specifically how SOP, 5S and problem solving can be used to implement administrative and engineering controls resulting in a safe workplace and increasing level of confidence for the operators working within the plant.

EVALUATION OF INDOOR ENVIRONMENT CONDITIONS IN OFFICES LOCATED IN BUILDINGS WITH LARGE GLAZED AREAS

2008 ◽  
Vol 14 (1) ◽  
pp. 39-44 ◽  
Author(s):  
Lina Šeduikytė ◽  
Valdas Paukštys
Keyword(s):  
Relative Humidity ◽  
Field Study ◽  
Indoor Environment ◽  
Subjective Evaluation ◽  
Heating Season ◽  
Dry Skin ◽  
Average Temperature ◽  
Average Relative Humidity ◽  
Indoor Spaces ◽  
Objective And Subjective Evaluation

The field study was carried out during the heating season in two Lithuanian office buildings with large glazed areas. The methodology was prepared for evaluating indoor microclimate parameters while using objective and subjective evaluation. The results show that the average temperature in all tested offices was in the range of optimal zones, but in some offices the average temperature was not in compliance with the recommended temperature for offices. During the subjective evaluation, respondents working in these offices identified complains because of too high temperatures, stuffy air and irritation in eyes. The average relative humidity measured in all tested offices was not in compliance with the optimal requirements. Such SBS symptoms as irritation in eyes, cough and dry skin of the hands were identified as the most frequent symptoms in the second tested building. Main indoor microclimate problems arising in buildings with large glazed areas were related to overheating indoor spaces because of the direct sun and improper ventilation. Santrauka Straipsnyje nagrinėjamos patalpų mikroklimato sąlygos pastatuose esančiuose biuruose, turinčiuose didelius įstiklintus plotus. Didelių skaidrių atitvarų plotų įrengimas pastatuose ne tik didina energijos sąnaudas pastatams šildyti, vėsinti ir orui kondicionuoti, bet ir sukuria mikroklimato sąlygas, kuriose dirbantys žmonės dažnai patiria šiluminį diskomfortą, nors aplinkos parametrai atitinka normų reikalavimus. Natūriniams patalpų mikroklimato tyrimams sukurta patalpų mikroklimato tyrimo metodika, kuri sieja objektyvius ir subjektyvius tyrimo metodus patalpų sąlygoms optimaliai įvertinti. Patalpų mikroklimato sąlygos tiksliausiai įvertinamos pagal patalpų mikroklimato parametrų matavimo, papildyto subjektyvaus mikroklimato sąlygų įvertinimu, apibendrintos analizės rezultatus.

scholarly journals Treatment with Dry Hydrogen Peroxide Accelerates the Decay of Severe Acute Syndrome Coronavirus-2 on Non-porous Hard Surfaces

2021 ◽  
Author(s):  
Yan-Jang S. Huang ◽  
Ashley N. Bilyeu ◽  
Wei-Wen Hsu ◽  
Susan M. Hettenbach ◽  
Joshua L. Willix ◽  
...  
Keyword(s):  
Hydrogen Peroxide ◽  
Infectious Virus ◽  
Mitigation Strategies ◽  
Control Group ◽  
Ambient Atmosphere ◽  
Surface Areas ◽  
Glass Slides ◽  
Pathogen Reduction ◽  
Indoor Spaces ◽  
Hydrogen Peroxide Vapor

Abstract Background. Disinfection of contaminated or potentially contaminated surfaces has become an integral part of the mitigation strategies for controlling coronavirus disease 2019. Whilst a broad range of disinfectants are effective in inactivating severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), application of disinfectants has a low throughput in areas that receive treatments. Disinfection of large surface areas often involves the use of reactive microbiocidal materials, including ultraviolet germicidal irradiation, chlorine dioxide, and hydrogen peroxide vapor. Albeit these methods are highly effective in inactivating SARS-CoV-2, the deployment of these approaches creates unacceptable health hazards and precludes the treatment of occupied indoor spaces using existing disinfection technologies. Deployment of dry hydrogen peroxide (DHP) is an emerging pathogen reduction technology, which produces hydrogen peroxide in the ambient atmosphere at 5 and 25 parts per billion using a commercially available catalytic unit. The low concentration of hydrogen peroxide released using DHP technology has been found to be tolerated by humans in indoor spaces and is effective in inactivating bacterial pathogens responsible for nosocomial infections. In this study, the feasibility of using DHP in inactivating SARS-CoV-2 on contaminated surfaces in large indoor spaces was evaluated. Methods. Glass slides were inoculated with SARS-CoV-2 and treated with DHP for up to 24 hours. Residual infectious virus samples were eluted and titrated in African green monkey VeroE6 cells. Results. In comparison with the observed relatively high stability of SARS-CoV-2 on contaminated glass slides in the control group, residual infectious titers of glass slides inoculated with SARS-CoV-2 were significantly reduced after receiving 120 minutes of DHP treatment. Conclusions. The accelerated decay of SARS-CoV-2 on contaminated glass slides suggests that treatment with DHP can be an effective surface disinfection method for occupied indoor spaces.

scholarly journals INDOOR SPACE ROUTING GRAPHS: VISIBILITY, ENCODING, ENCRYPTION AND ATTENUATION

2018 ◽  
Vol XLII-4 ◽  
pp. 579-585
Author(s):  
G. Sithole
Keyword(s):  
Path Planning ◽  
Indoor Environment ◽  
Indoor Navigation ◽  
Indoor Space ◽  
The Third ◽  
Future Paper ◽  
Spatial Geometry ◽  
Novel Method ◽  
Third Dimension ◽  
Indoor Spaces

<p><strong>Abstract.</strong> The conventional approach to path planning for indoor navigation is to infer routes from a subdivided floor map of the indoor space. The floor map describes the spatial geometry of the space. Contained in this floor map are logical units called subspaces. For the purpose of path planning the possible routes between the subspaces have to be modelled. Typical these models employing a graph structures, or skeletons, in which the interconnected subspaces (e.g., rooms, corridors, etc.) are represented as linked nodes, i.e. a graph.</p><p>This paper presents a novel method for creating generalised graphs of indoor spaces that doesn’t require the subdivision of indoor space. The method creates the generalised graph by gradually simplifying/in-setting the floor map until a graph is obtained, a process described here as chained deflation. The resulting generalised graph allows for more flexible and natural paths to be determined within the indoor environment. Importantly the method allows the indoor space to be encoded and encrypted and supplied to users in a way that emulates the use of physical keys in the real world. Another important novelty of the method is that the space described by the graph is adaptable. The space described by the graph can be deflated or inflated according to the needs of the path planning. Finally, the proposed method can be readily generalised to the third dimension.</p><p>The concept and logic of the method are explained. A full implementation of the method will be discussed in a future paper.</p>

scholarly journals Impact of Ventilation Strategy on the Transmission of Outdoor Pollutants into Indoor Environment Using CFD

2021 ◽  
Vol 13 (18) ◽  
pp. 10343
Author(s):  
Murtaza Mohammadi ◽  
John Calautit
Keyword(s):  
Air Quality ◽  
Indoor Air Quality ◽  
Indoor Air ◽  
Indoor Environment ◽  
Dispersion Model ◽  
Personal Exposure ◽  
Health Impact ◽  
Concentration Data ◽  
Pollution Dispersion ◽  
Indoor Spaces

The transition to remote working due to the pandemic has accentuated the importance of clean indoor air, as people spend a significant portion of their time indoors. Amongst the various determinants of indoor air quality, outdoor pollution is a significant source. While conventional studies have certainly helped to quantify the long-term personal exposure to pollutants and assess their health impact, they have not paid special attention to the mechanism of transmission of pollutants between the two environments. Nevertheless, the quantification of infiltration is essential to determine the contribution of ambient pollutants in indoor air quality and its determinants. This study evaluates the transmission of outdoor pollutants into the indoor environment using 3D computational fluid dynamics modelling with a pollution dispersion model. Naturally ventilated buildings next to an urban canyon were modelled and simulated using Ansys Fluent and validated against wind tunnel results from the Concentration Data of Street Canyons database. The model consisted of two buildings of three storeys each, located on either side of a road. Two line-source pollutants were placed in the street, representing traffic emissions. Three internal rooms were selected and modelled on each floor and implemented with various ventilation strategies. Results indicate that for a canyon with an aspect ratio of 1, indoor spaces in upstream buildings are usually less polluted than downstream ones. Although within the canyon, pollution is 2–3 times higher near the upstream building. Cross ventilation can minimise or prevent infiltration of road-side pollutants into indoor spaces, while also assisting in the dispersion of ambient pollutants. The critical configuration, in terms of air quality, is single-sided ventilation from the canyon. This significantly increases indoor pollutant concentration regardless of the building location. The study reveals that multiple factors determine the indoor–outdoor links, and thorough indexing and understanding of the processes can help designers and urban planners in regulating urban configuration and geometries for improved indoor air quality. Future works should look at investigating the influence of indoor emissions and the effects of different seasons.

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